/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.runtime.concurrent;

import org.apache.flink.runtime.rpc.MainThreadValidatorUtil;
import org.apache.flink.runtime.testutils.DirectScheduledExecutorService;

import javax.annotation.Nonnull;

import java.util.concurrent.Callable;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;

/**
 * Adapter class for a {@link ScheduledExecutorService} or {@link ScheduledExecutor} which shall be
 * used as a {@link ComponentMainThreadExecutor}. It enhances the given executor with an assert that
 * the current thread is the main thread of the executor.
 */
public class ComponentMainThreadExecutorServiceAdapter implements ComponentMainThreadExecutor {

    private final ScheduledExecutor scheduledExecutor;

    /** A runnable that should assert that the current thread is the expected main thread. */
    private final Runnable mainThreadCheck;

    public ComponentMainThreadExecutorServiceAdapter(
            final ScheduledExecutorService scheduledExecutorService, final Thread mainThread) {
        this(new ScheduledExecutorServiceAdapter(scheduledExecutorService), mainThread);
    }

    public ComponentMainThreadExecutorServiceAdapter(
            final ScheduledExecutor scheduledExecutor, final Thread mainThread) {
        this.scheduledExecutor = scheduledExecutor;
        this.mainThreadCheck =
                () -> {
                    assert MainThreadValidatorUtil.isRunningInExpectedThread(mainThread);
                };
    }

    public static ComponentMainThreadExecutor forMainThread() {
        final Thread main = Thread.currentThread();
        return new ComponentMainThreadExecutorServiceAdapter(
                new DirectScheduledExecutorService() {
                    @Override
                    public void execute(Runnable command) {
                        assert MainThreadValidatorUtil.isRunningInExpectedThread(main);
                        super.execute(command);
                    }
                },
                main);
    }

    /**
     * Creates a test executor that delegates to the given {@link ScheduledExecutorService}. The
     * given executor must execute all submissions with the same thread.
     */
    public static ComponentMainThreadExecutor forSingleThreadExecutor(
            @Nonnull ScheduledExecutorService singleThreadExecutor) {
        final Thread thread =
                CompletableFuture.supplyAsync(Thread::currentThread, singleThreadExecutor).join();
        return new ComponentMainThreadExecutorServiceAdapter(singleThreadExecutor, thread);
    }

    @Override
    public void assertRunningInMainThread() {
        mainThreadCheck.run();
    }

    @Override
    public ScheduledFuture<?> schedule(
            final Runnable command, final long delay, final TimeUnit unit) {
        return scheduledExecutor.schedule(command, delay, unit);
    }

    @Override
    public <V> ScheduledFuture<V> schedule(
            final Callable<V> callable, final long delay, final TimeUnit unit) {
        return scheduledExecutor.schedule(callable, delay, unit);
    }

    @Override
    public ScheduledFuture<?> scheduleAtFixedRate(
            final Runnable command,
            final long initialDelay,
            final long period,
            final TimeUnit unit) {
        return scheduledExecutor.scheduleAtFixedRate(command, initialDelay, period, unit);
    }

    @Override
    public ScheduledFuture<?> scheduleWithFixedDelay(
            final Runnable command,
            final long initialDelay,
            final long delay,
            final TimeUnit unit) {
        return scheduledExecutor.scheduleWithFixedDelay(command, initialDelay, delay, unit);
    }

    @Override
    public void execute(final Runnable command) {
        scheduledExecutor.execute(command);
    }
}
